US District Court Judge Richard Stearns says James ‘Whitey’ Bulger did not have ‘license to kill’

US District Court Judge Richard Stearns today delivered a major blow to James “Whitey’’ Bulger’s defense by ruling that no law allows an immunized witness to commit murders after they agree to cooperate with federal law enforcement.

Stearns wrote that Bulger, or other federal informants, may avoid prosecution for crimes they commit prior to becoming an informant or a cooperating witness as part of an agreement with law enforcement.

But no such authority exists for prospective crimes.

Advertisement - Continue Reading Below

“The court concludes that any grant of prospective immunity to commit murder was without authorization and is hence unenforceable under any circumstances,’’ Stearns wrote in a 20-page order released today. “An immunity agreement cannot as a matter of public policy license future criminal conduct.’’

Stearns added: “A license to kill is even further beyond the pale and one unknown even in the earliest formulations of the common law... The government argues, correctly, that the authority to grant immunity from prosecution – and therefore the court’s deference to the decision to issue such grants – does not extend to crimes committed in futuro.’’

According to Stearns, Bulger’s defense team, led by Boston attorney J. W. Carney Jr., has provided only general information about the cooperation agreement, including Bulger’s claim that an immunity agreement with Jeremiah O’Sullivan when O’Sullivan ran the New England Organized Crime Strike Force.

O’Sullivan has since died, and Bulger claims an oral immunity agreement was reached with O’Sullivan decades ago.

While dismissing Bulger’s claim he was had a license to kill, Stearns said he wants to decide himself whether jurors in Bulger’s upcoming trial will hear about his alleged agreement with the late O’Sullivan.

“Resolution of the defendant’s immunity claims requires an inquiry into the existence, scope and validity of the alleged agreement [Bulger] made with the New England Organized Crime Strike Force Chief Jeremiah O’Sullivan,’’ Stearns wrote. “It does not require presentation of evidence regarding the commission of any of the nineteen murders or other crimes with which the defendant is charged.’’

Carney has said that Bulger will testify in his own defense during his trial and will lay out the details of his agreement with O’Sullivan.

Stearns said he wants to address the question before then.

“Under these circumstances, it would present a disservice to judicial economy and the orderly administration of justice to sit idly by awaiting the raising of an objection that is now ripe and which defendant has unequivocally indicated his intent to invoke,’’ Stearns wrote.

Stearns has been weighing a request by US Attorney Carmen Ortiz’s office to prohibit Bulger from presenting his immunity defense to jurors when he goes to trial in June. Bulger is charged in a sweeping federal racketeering case with participating in 19 murders in the 1970s and 1980s.

On Friday, the Justice Department and the FBI said they have been unable to locate any documents that support Bulger’s claim that he was authorized to commit crimes, including murder, according to a government memorandum filed in court Friday.

Bulger, 83, says that former federal prosecutor O’Sullivan, who died in 2009, verbally promised him lifetime immunity decades ago, though he has never provided the date he says it was granted.

The affidavit filed Friday, a Justice Department official who supervised O’Sullivan during much of the time O’Sullivan was head of the New England Organized Crime Strike Force, said O’Sullivan never discussed giving Bulger immunity and would not have had the authority to grant it on his own.

This is a developing story. Check bostonglobe.com and boston.com for updates.